The present invention relates to an improved method for regenerating water softener in a washing machine, particularly in an automatic dishwashing machine.
As is common knowledge, the water supply circuit of machines such as automatic dishwashing machines is usually provided with a water softening device containing active resins that are regenerated periodically by the addition of metered quantities of brine. This brine is formed by passing water through a salt reservoir. In order that the extent of the regeneration of the water softener corresponds to the actual degree of hardness of the supply water, the quantity of brine to be metered into the water softening device is appropriately adjusted.
In an alternative method, the water softener is regenerated through the addition of a constant quantity of brine thereto, the salt concentration of which is varied accordingly in this case. Such a method is disclosed, for instance, in EP-B-0 219 704, in which mechanical means are provided to vary the salt concentration by changing the length of the average flow path of a predetermined volume of regeneration water passing through a mass of salt situated inside a specially provided reservoir. In this way, in the case of a very high degree of hardness of the supply water, it is practically possible to do away with the need of using considerable volumes of brine which might otherwise overflow into the wash tank of the machine and give rise to corrosion problems. On the other hand, the means for adjusting the salt concentration, which are housed within the salt reservoir, may turn out to be quite difficult to reach and their adjustment may turn out to be undesirably inaccurate.